Art of well drilling



June 17, 1941. c w FRQOME ET AL 224631-18 ART OF WELL DRILLING Filed larch 14, 1953 5| @1 3. s! '11-- 14 13 a I 1 I 1 B 14-" Fl-Pi 4 1 l 9 E 13 :INVENTORVS g 14 Clarence WFroomeiFranlrCfiayd BY @M 2 ATTORNEY.

Patented June 17, 1941 ART or WELL DRILLING Clarence Ward Froome and Frank Cochran 'Boyd, Los Angeles County, Calii., assignors to Union Oil Company of California, Los Angeles, Calif., a corporation of California Application March 14, 1938, Serial No. 195,710

5 Claims:

The present invention relates to the art of drilling, and more particularly pertains to a new and improved type of drill pipe to be used in oil well drilling operations. This invention also includes the method of producing the improved drill pipe described herein.

In the usual rotary method of drilling oil or like wells, a drill bit is suspended from the lower end of a string of drill pipe extending from the surface to the lower end of the bore where the drilling is being realized. The upper end of the drill pipe is rotated by any known means, as for example, a rotary table, which rotates said pipe and simultaneously permits the gradual lowering of the drill pipe and bit as the drilling progresses. As is obvious, the actual boring is produced by the rotation of the bit pressing against the bottom of the bore hole, this rotation being imparted to the bit by the rotation of the whole string of pipe, For the purpose of lubrication of the bit, as well as for the removal or withdrawal of the cuttings produced during such drilling, it is the usual practice to circulate a mud solution, This circulation may be downwardly through the drill pipe, through the bit, and upwardly through the annular space between the outer walls of the pipe and the walls of the bore or of the casing, if such has been placed Within the drilled portion of the bore. The mud circulation may also be in a direction opposite to that described above.

The present day drilling operations, and particularly oil well drilling, is realized under extremely difiicult technical conditions. Thus, the usual type of drill pipe employed in such drilling operations is a hollow steel pipe which has an 1 ',outside diameter of anywhere from about 6 or 7 inches to as little as slightly over 2 inches in the case of some redrilling or very deep drilling operations. The present day oil Well drilling extends to depths of anywhere from one to two miles. Obviously, to cause the boring, the drill bit must press against the formation being cut. It is thus clear that with rotation speeds of anywhere from 60 to 300 and 400 revolutions per minute and with a hollow relatively slender and excessively long drill pipe, the bit on the end of which abuts against the formation being drilled, excessive stresses are generated in the drill pipe. Also, such drilling causes the swinging or side movement of the drill pipe which creates fatigue of the metal resulting in the breaking of the drill pipe. Also, such lateral movements of the drill pipe prevent straight hole drilling. In other words, instead of the well bores being vertical, they frequently slant ofi and the bore hole is found to be crooked, with the result that it becomes very difiicult to install protective casing in such wells and the recovery of the oil from such holes becomes excessively diiiicult and frequently impossible, particularly when the ordinary type of pumps is employed.

It is therefore the main object of the present invention to provide a new and improved drill pipe which will avoid the above difllculties and which will permit the drilling of straight holes with the minimum occurrence of twist-offs or other breakage of the drill pipe. It is another object of the present invention to provide a method for drilling straight bore holes in which the drill pipe is maintained substantially vertically and without lateral or side movements during the drilling operations. A further object of the present invention is to provide a method for the manufacture of the above described improved drill pipe.

It has now been discovered that the above and other objects'may be attained by providing the surface or walls of the drill pipe with spirally disposed corrugations. More specifically stated, one of the specific embodiments of 'the present invention consists in a drill pipe, the walls of which are in the form of spirally disposed concavoconvex corrugations.

The invention further comprises a drill pipe string consisting of a. series of interconnected sections of drill pipe, the walls of each of which are spirally corrugated between the joints connecting the individual sections of the drill pipe. The invention still further resides in the use of the above described improved drill pipe string in rotary drilling of bore holes.

Although it is not the intention to limit the present invention by any theory, the following discussion is presented as the present opinion of the reasons for claiming the advantages of the improved drill pipe constituting one of the objects of the present invention, it being clearly understood that the invention is not predicted on any theory but is to be limited only by the appended claims.

As outlined above, ordinary oil well drilling, when using rotary drilling equipment, employs a mud solution for purposes of lubrication, removal of the cuttings, and also to prevent blowouts in case a high pressure zone is encountered during drilling. Ordinarily, this mud fluid or solution is continuously pumped under pressure downwardly through the drill pipe, through special openings in the drill bit attached to the lower end of the drill pipe, and upwardly through the annular space surrounding the drill pipe. when the mud reaches the surface, it is through settlers to remove the cuttings, etc., and is reconveyed backintothedrillpipe. Whenusingtheimproved spirally corrugated drill pipe constituting one of the objects of the present invention, the mud fluid thus conveyed downwardly through the drill pipe will move spirally through such drill pipe because of the presence of the veins or corrugations. Simultaneously, themud fluid rising in the annular space surrounding the drill pipe will also move spirally but obviously in the opposite direction. Also, because oi. the spiral concave-convex corrugations of the walls of the drill pipe, the paths of the downwardly moving stream and of the upwardly moving stream will be opposite. Thus, considering the movements of the mud fluids from the upper end of the drillpipe, if the spiral movement of the downwardly moving stream is clockwise then the path of the upwardly moving stream will be counter-clockwise, and vice versa, it being understood that the spiral corrugations of the drill pipe may be either "right handedor left handed. These opposite spiral movements or paths of the mud fluid will tend to hold the drill pipe as if in a packed bearing, thereby tending to'prevent the side movements or side flapping of the drill pipe during rotation. Furthermore, when using ordinary cylindrical drill pipe, the mud fluid rising in the annular space between the outer walls of the drill pipe and the walls of the bore or the casing therein, moves substantially vertically. Therefore, if a portion of the drill pipe is not exactly concentric with the longitudinal axis of the bore hole, the mud fluid merely rises through said annular space without exerting any pressure or tendency to align said drill pipe. On the other hand, the spiral movement of the mud fluid through the annular space will tend to align the longitudinal axis of the drill pipe with the longitudinal axis of the bore hole since any approach of any part of the outer walls of the drill pipe to the walls of' the bore hole orof the casing will tend to impinge on the uniform travel or movement of the mud fluid, the fluid resisting such impingement, and forcing the drill pipe into or towards the center of the bore hole.

The invention may therefore be still further stated to reside in a process of drilling wells such as oil wells, said process consisting in rotating a string of drill pipe of the type constituting one of the objects of the present invention, and conveying a mud solution countercurrently and along diametrically opposite spiral paths on the two sides of the walls of said drill pipe, thereby tending to maintain the drill pipe in the center of the well bore and preventing any side or lateral movement of said drill pipe. The invention still further resides in a structure for drilling oil wells, this structure comprising or including a drill pipe string consisting of a series of interconnected sections of drill pipe, each of said sections having its walls spirally corrugated in either direction, a drill bit attached to the lower end of said drill pipe, and means adapted to cause a spiral movement of mud fluid in one direction through the interior of the drill pipe and in the other and opposite direction around said drill pipe, thereby preventing or hindering any lateral or side movement of the pipe and causing the drill bit to drill a straight bore.

The invention may be more fully understood by reference to a description of the accompanying drawing, in which:

Figure lisalongitudinalview,partlyinsection. of the drill 9 9 Figure 2 is a section taken along line 2-2 of Figure 1; and

Figure 3 is a view, partly diagrammatic and partly in section, showing the rotary drilling of a well bore with a drill pipe string constituting one of the phases of this invention.

Corresponding parts are designated in all the figures by the same reference characters.

Referring with particularity to the drawing, and more specifically to Figure 1 thereof, this figure shows the improved drill pipe indicated generally by reference numeral l0. As shown in this figure, the ends H and I2 of the pipe iii are cylindrical in shape, and are provided with threads l3 for attachment to coupling H. Although an ordinary coupling is shown as joining to sections of the pipe it, it is to be understood that other means may be employed. Thus, the ordinary box and pin type or tool joint couplings may be used instead of the coupling 14.

With the exception of the end portions II and I2, the walls of the drill pipe Ill are in the form of spirally disposed fluted portions or corrugations designed by numeral ll. These corrugations I! extend spirally along the whole length of pipe Ill, thus forming alternate concave and convex surfaces IB and I9 more particularly disclosed in Figure 2 of the drawing.

As shown in Figure 3 of the drawing the drill pipe Ill constituting one phase of the invention is to be used for drilling oil wells. For this purpose the individual sections of the improved pipe Ill are connected to each other as by means of coupling l4, any type of drill pipe 22 being attached to the lower end of such improved drill pipe string. The upper end of the drill pipe string is connected as by means of a tool joint or coupling 23 to a kelly 24, this being a hollow pipe having a square outside section. The kelly 24 passes through a rotary table generally indicated by numeral 25 and is held therein by spiders or holders 26 which cause the kelly of the drill pipe to rotate together with the rotary table 25 and simultaneously permit gradual lowering of the drill pipe string as drilling progresses. As shown, the drill pipe string and the bit are suspended in a bore hole 28, the upper portion of which is provided with a casing 29. This casing carries a cover or cap 30 at its upper end, the drill pipes in passing through an opening 3|. The upper end of the casing 29 is further provided with a pipe 33 equipped with a valve 34, the purposes of which will be described more fully hereinbelow.

In drilling operations the improved drill pipe string l0 carrying the bit 22 at its lower end is suspended in the bore hole 28 until the bit reaches the bottom of the hole. The drilling is realized by the rotation of the rotary table 25 which transmits its movement through kelly 24, and drill pipe string ill to the bit 22. The circulation of the mud fluid may be realized by forcing said mud fluid under pressure through the annular space 36 in the kelly, down through the interior of the drill pipe Ill and out through port or opening 31 in drill bit 22. The mud then rises through the annular space 38 between the outer walls of the drill pipe and the inner walls of the bore hole 28 and the casing 29. If the upper end of the casing is capped as shown in Figure 3 the mud fluid is then discharged through valved pipe 33. When the circulation of the mud fluid is in the direction just described it is sometimes unnecessary to cap the upper end of the casing, the mud fluid overflowing from said upper end of the casing 29 into a sump or other receptacle for the mud fluid. It is of course obvious that the circulation may be caused to flow in the opposite direction, in which case the mud fluid may be forced through pipe 33, down through the annular space 38 and up through the interior of the drill pipe l0.

As previously described, the provision of the spirally disposed concave or convex flutes or corrugations l1, constituting the walls of the improved drill pipe Ill causes a. spiral movement of the mud fluid forced downwardly through the drill pipe. This is more particularly shown in Figure 1 wherein the arrows A and B indicate the direction of the downwardly moving mud fluid stream. The simultaneous upward moving stream of mud fluid is also along a spiral path as this is shown by arrow C in Figure 3. As indicated, thetwo spiral movements are in opposite directions, this being due to the aforementioned corrugations II. It has been discovered that such spiral movements of the mud .fiuid dur- ?ing drilling operations tends to hold the drill pipe l against side flapping or side movements, thereby tending to cause the drilling of straight bore holes. I

The pipe constituting one of the objects of this invention may be manufactured by difl'erent methods. Thus, it is possible to first form the tube so that it comprises a cylindrical body having the proper or desirable dimensions and wall thickness. Thereafter, the tube thus made may be run or passed through a specially designed rolling mill, said mill causing the formation of the spirally disposed concavo-convex flutes or corrugations on the pipe. This rolling mill could be so designed as to leave the end sections of I the pipe blank, 1. e. without the spirals. This is for the purpose of leaving space on said pipe for the cutting of suitable threads which are used for the screwing on of the couplings or tool joints usually employed for the connection of the adjoining sections of drill pipe. In the alternative, the tube may be first spiralled along the whole length thereof, and then the end portions of such pipe may be re-rounded and/or upset to accommodate the aforementioned threads. It is to be understood, however, that the provision of these threads is not absolutely essential since it is possible to weld or otherwise connect the couplings or tool joints to the respective ends of the spiral drill pipe. Thus, for example, the

' tool joints or couplings to be employed in connection with the drill pipe constituting one of the objects of this invention, may be forged, machined, or otherwise provided with internal spirals adapted to fit the spiral pipe. These connections may then be placed over the ends of the drill pipe and welded in place.

It is thus obvious that many modifications of the invention may be made within the scope of the invention, and it is to be understood, therefore, that there is no intention to be limited by any specific details herein set forth. It is to be further understood that the invention is to be limited only by the appended claims.

We claim:

1. As a new article of manufacture, a drill pipe, the external and internal walls of which are in the form of spirally disposed concavo-convex corrugations.

2. As a new article of manufacture, a drill pipe having its external and internal walls in the form of concave-convex spirally disposed corrugations, the ends of said drill pipe being provided with means adapted to receive couplings.

3. In a structure according to claim 2, where,- in the ends of the drill pipe are circular in crosssection and are provided withthreads adapted to receive couplings.

4. A structure for drilling oil wells which comprises a drill pipe string consisting of a series of interconnected drill pipe sections, the external and internal walls of each ofwhich are in the form of spirally disposed corrugations, a drill bit attached to the lower end of said drill pipestring, means to actuate said drill pipe string and to cause its rotation, and means adapted to introduce a mud fluid and to cause its spiral movement in one direction on one side of the walls of the drill pipe and in an opposite spiraldirection on the other side of the walls of said drill pipe string.

5. In a structure according to claim 4, where, in the last mentioned means convey the mud fluid downwardly and in a spiral direction through the interior of the drill pipe, and upwardly and in the opposite spiral direction through the annular space around said corrugated drill Pipe.

FRANK COCHRAN BOYD. CLARENCE WARD PROOME. 

